I have a few issues left on the vehicle, check engine light, which after I got my factory service manuals I was able to decode by shorting 2 pins on the header you plug into, god I love older vehicles... looks like a oxygen sensor.

Anyway, So the vibration Notice it at higher speeds, and only when I step on the gas, constant vibration. I let off the gas and it seems to go away, so Im thinking mebbie a driveline, or ujoint issue? Anyways I was wondering... could I remove the rear drive line, and run in 4wd (so only the front would work) and see if the vibration goes away? or is that a nono

If its ok, is it hard to do? Any precautions?

 

Sounds like pinion bearing in rear end is going out. I just went through this issue on my 1988 Blazer. Could also be the u-joints too. Put the truck in park, go underneath and see if you can move the rear driveshaft. If you can, you most likely need u-joints, but I think your problem is in the rear differential.

 

It was the U joints, it had the factory ones on there, 210,000 miles were not kind...

Now I got another issue =) I just step on my pedal a little bit to say 30mph, and keep it there, its like the engine gets quiet and loose power, stomp on the gas and it comes back for a little bit then same thing.

normal things done so far, injector cleaner, plugs, fuel filter, since the u joints were original, I wonder if the exhaust is, Im hoping its a collapsed Cat converter, because if its not, im looking at engine issues =(

 

Glad you got your issue fixed. As for the cat converter theory, does your transmission shift a little late or a little off? If yes, this would confirm a clogged cat. Also wondering when was the last time a tune up was done on your truck?

 

I had the same problem. Spark plugs were gapped incorrectly. I'd check those. .035 is the correct gap